Windows 7 : Using CDs and DVDs - What Kind of Drive Do I Have?

1. Understanding CDs and DVDs

Even though CDs and DVDs look exactly alike, there's a big difference in capacity. A CD holds about 650–700 MB of data. A DVD holds about 4.7 GB (or about 4,700 MB). In other words, one DVD can hold more information than six CDs. This is also why albums are sold on CDs and movies on DVDs — there isn't enough room on a CD to store a feature-length movie.

The newest media type, Blu-ray, has the same physical dimensions as CDs and standard DVDs, but uses a blue-violet laser that has a shorter wavelength than the red laser used on older formats. This shorter wavelength makes it possible for Blu-ray media to hold up to 50 GB (using dual-layer media). Because of its higher capacity, Blu-ray offers better image quality for movies than standard DVD. However, you must have a Blu-ray drive to play Blu-ray media.

To complicate matters, many different kinds of CDs and DVDs are available, including CD-ROM, CD-R, CD-RW, DVD-R, DVD-RW, DVD+R, DVD+RW, and DVD-RAM. So let's untangle that mess, starting with the most common types of disks — the CD-ROM and DVD-ROM.

1.1. CD-ROM and DVD-ROM

The ROM in CD-ROM and DVD-ROM stands for read-only memory. The term "read only" means you can read (or play) the contents of the disk whenever you want. The disk is not writable. You can't add new files to the disk, remove files from the disk, or change files that are already on the disk.

1.2. CD-R, DVD-R, and DVD+R

The R in CD-R, DVD-R, and DVD+R stands for recordable. These are often referred to as distribution media because they're the blank disks that software companies, record companies, and the movie industry use to stamp out thousands of copies of the programs, albums, and movies they sell. In other words, they buy -R disks to create the -ROM disks that they sell you.

1.3. CD-RW, DVD-RW, DVD+RW

The RW in CD-RW, DVD-RW, and DVD+RW stands for read/write. The -RW disks are often called backup media. You can use a CD-RW, DVD-RW, or DVD+RW disk to back up important files. You can erase the disk and start over if you like, and you can delete individual files. In short, the -RW disks are much more like hard disks, just not as fast!

1.4. Data CD versus audio CD

CDs come in two capacities, commonly referred to as data CDs and audio CDs. A data CD has a capacity of about 650 MB, or enough space to store about 74 minutes worth of music. Those are best to use when your goal is to use the CD to store backup copies of files on your hard disk, or to distribute copies of files to other people.

An audio CD has a capacity of about 700 MB, or enough space to store about 80 minutes worth of music. Those are best to use when you want to create your own custom music CDs to play in your car stereo or in a CD player. 

1.5. DVD- versus DVD+

There are two DVD standards to consider, although the differences have little to do with DVDs as used in computers. They're more subtle differences having to do with how DVDs store data for watching movies on TV. So for the average computer user, choosing between a + and — DVD is largely a matter of knowing what works with your DVD player, DVD burner, and whatever other equipment you have.

Disc, Disk, What's the Difference?

The only difference between a "disk" and a "disc" is the spelling. Computer people usually spell it "disk." The people who invented CDs and DVDs decided to spell it "disc." But no matter how you spell it, it's a medium on which you can store information. I'll use "disc" in places you're likely to see it spelled that way.

2. What Kind of Drive Do I Have?

If you just purchased a new computer, you might not be sure what type of drive you have. Getting information about your CD/DVD drive isn't difficult. You can get some information right from your Computer folder. First make sure there isn't a disk in the drive. Then open your Computer folder and take a look at the icon for the empty drive. The icon and description should provide some clues. To get more information, you can right-click that icon, choose Properties, and click the Hardware tab for more specific information. For example, in Figure 1, drive D: is a DVD/CD-RW drive.

Figure 1. Icon and Properties for a DVD drive.

There's also a System Information window you can use to get specs on your system. Click the Start button, type sys, and click System Information on the Start menu. In the window that opens, click the + sign (if any) next to Components and click CD-ROM. The pane to the right shows detailed information about the drive as in the example shown in Figure 2.

Unfortunately, knowing the make and model of the drive doesn't tell you all the different types of disks it can handle. For instance, the Hitachi drive shown previously can read and write virtually all CD and DVD disk types, but there's no indication of that in either figure. After you know the make and model of the drive, you can search the manufacturer's Web site for the model number for more detailed specs. Or you can use a general search engine like Google or Bing to search for both the make and model name (HL-DT-ST in my example).

Figure 2. System Information about a CD/DVD drive.

Of course, there's always the old-fashioned method of calling your computer manufacturer on the phone, or contacting them by e-mail, and asking about the drive. At the very least, you'll need to know the model of your computer. Then ask them what kinds of disks the drive can handle.